1. Field of the Invention
The present invention relates to a fuel temperature sensing device that senses fuel temperature for each cylinder of an internal combustion engine.
2. Description of Related Art
In a conventional common internal combustion engine, a fuel temperature sensor that senses fuel temperature is provided in a discharge port of a pump that supplies fuel to an injector. However, in recent years, it is required to sense the fuel temperature at a position near an injection hole of the injector in some cases. Hereafter, the fuel temperature at a position near the injection hole of the injector will be referred to as INJ fuel temperature. In the above-described construction that senses the fuel temperature in the pump discharge port, the fuel temperature sensor is affected by a heat generated when the fuel is compressed by the pump, and ambient temperature in the discharge port differs from the ambient temperature in the injection hole. Therefore, it is difficult to sense the INJ fuel temperature correctly in such the construction.
The sensing of the INJ fuel temperature is required in a following case, for example. A technology described in Patent document 1 (JP-A-2009-57924) provides fuel pressure sensors for sensing fuel pressure to injectors of respective cylinders. The technology senses a fuel pressure change (fuel pressure waveform) occurring with injection to calculate a change of an actual injection rate (injection rate waveform). Eventually, the technology enables sensing of injection start timing, injection end timing, an injection quantity and the like. However, the above-described fuel pressure waveform turns into different waveforms depending on the fuel temperature (INJ fuel temperature) in the injection hole, from which the fuel is injected then. Therefore, it is required to sense the INJ fuel temperature and to calculate the injection rate waveform by correcting the fuel pressure waveform based on the sensed NJ fuel temperature.